Scroll type compressor

ABSTRACT

A scroll type compressor includes a housing, a rotary shaft rotatably supported in the housing and having an eccentric pin projecting from an end of the rotary shaft, a fixed scroll member and a movable scroll member facing the fixed scroll and forming a pair of compression chambers therewith. The scroll type compressor further includes a balancer-integrated bush having an eccentric hole to receive the eccentric pin and disposed between the eccentric pin and the movable scroll. The balancer-integrated bush is configured to receive rotational force from the rotary shaft to cause the movable scroll member to make an orbital movement. An elastic member provided between the rotary shaft and the balancer-integrated bush in an elastically deformed state to always apply a preload to the movable scroll member via the balancer-integrated bush in a direction that increases an orbital radius of the movable scroll member.

BACKGROUND OF THE INVENTION

The present invention relates to a scroll type compressor.

A scroll type compressor employs a link mechanism such as a swing link mechanism and a slide link mechanism. The Patent Application Publication No. 2009-127524 discloses a swing link mechanism of a scroll type compressor. These link mechanisms enable to vary the orbital radius of the movable scroll member of the scroll type compressor. Even if any scroll member has a machining tolerance or an assembly tolerance, the scroll members can be set in contact with each other with an appropriate contact pressure. In addition, the movable scroll member having a variable orbital radius can protect the wrap surface of the scroll members against any foreign matter between the scroll members.

With a scroll type compressor having a mechanism for the variable orbital radius of the movable scroll member, noise is likely to be generated by a collision between a rotary shaft and a bush during the starting and stopping of the compressor.

The present invention, which has been made in light of the problems mentioned above, is directed to providing a scroll type compressor which can reduce the noise generated during the operation or stopping of the compressor.

SUMMARY OF THE INVENTION

In accordance with an aspect of the present invention, there is provided a scroll type compressor including a housing, a rotary shaft rotatably supported in the housing and having an eccentric pin projecting from an end of the rotary shaft, a fixed scroll member and a movable scroll member facing the fixed scroll and forming a pair of compression chambers therewith. The scroll type compressor further includes a balancer-integrated bush having an eccentric hole to receive the eccentric pin and disposed between the eccentric pin and the movable scroll. The balancer-integrated bush is configured to receive rotational force from the rotary shaft to cause the movable scroll member to make an orbital movement. An elastic member provided between the rotary shaft and the balancer-integrated bush in an elastically deformed state to always apply a preload to the movable scroll member via the balancer-integrated bush in a direction that increases an orbital radius of the movable scroll member.

Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIG. 1 is a longitudinal sectional view showing an overall configuration of a compressor according to a first embodiment;

FIG. 2 is a plan view of a balancer-integrated bush provided in the compressor of FIG. 1, as viewed from electric motor side of the compressor;

FIG. 3 is a cross-sectional view of a rotary shaft, the balancer-integrated bush and an elastic member provided in the compressor of FIG. 1;

FIG. 4 is an exploded perspective view of the rotary shaft, the balancer-integrated bush and the elastic member of the compressor of FIG. 1;

FIG. 5 is a plan view of a movable scroll wrap of a movable scroll member and a fixed scroll wrap of a fixed scroll member of the compressor of FIG. 1;

FIG. 6 is a first plan view showing a dimensional relation of the rotary shaft and the balancer-integrated bush of the compressor of FIG. 1;

FIG. 7 is a second plan view showing another dimensional relation of the rotary shaft and the balancer-integrated bush of the compressor of FIG. 1;

FIG. 8 is a third plan view showing still another dimensional relation of the rotary shaft and the balancer-integrated bush of the compressor of FIG. 1;

FIG. 9 is a cross-sectional view of the rotary shaft, the balancer-integrated bush and the elastic member of a compressor in a comparative example;

FIG. 10 is a plan view of the rotary shaft, the balancer-integrated bush and the elastic member of a compressor according to a comparative example;

FIG. 11 is a plan view of the movable scroll wrap of the movable scroll member and the fixed scroll wrap of the fixed scroll member of the compressor according to a comparative example;

FIG. 12 is a perspective view of the rotary shaft, the balancer-integrated bush and the elastic member of a compressor according to a second embodiment.

FIG. 13 is a plan view of the rotary shaft, the balancer-integrated bush and the elastic member of the compressor of FIG. 12; and

FIG. 14 is a perspective view of the rotary shaft and the elastic member of the compressor of FIG. 12.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following will described embodiments of the present invention with reference to the accompanying drawings. The number or quantity of any part or element appearing in the following description, unless otherwise mentioned, may not be construed to limit the scope of the present invention. Identical or corresponding parts or elements will be denoted by the same reference numeral and the description thereof may be omitted if found redundant.

Referring to FIG. 1 showing a scroll type compressor 100 of a first embodiment in longitudinal sectional view (hereinafter simply referred to as compressor), the compressor 100 includes a housing 10, a compression mechanism 20, an electric motor 30 and a rotary shaft 40. The housing 10 includes a motor housing 11, an inner housing 12 and a discharge housing 13. These housings are made of a metal material such as an aluminum alloy.

The motor housing 11 has a bottomed cylindrical shape and a suction port (not shown) is formed through the side wall of the motor housing 11. The motor housing 11 has at the bottom thereof a bearing 41A that rotatably supports the rotary shaft 40 at one end thereof on the front side of the compressor 100. Numeral 41 designate an end surface of the rotary shaft 40 at the front end. A cover 14 is mounted to the bottom of the motor housing 11. A motor driving circuit 15A is disposed in a space 14A formed between the motor housing 11 and the cover 14.

The inner housing 12 is accommodated in the motor housing 11. The inner housing 12 includes a projection 12A having formed therein a recess 12B. A bearing 42A is provided in the projection 12A of the inner housing 12 and rotatably supports the other end of the rotary shaft 40 on the rear side of the compressor 100. Numeral 42 designates an end surface of the rotary shaft at the rear end. Thus, the rotary shaft 40 is rotatably supported at the opposite ends thereof by the bearing 41A and 42A. As will be described in details later, a balancer-integrated bush 60 is disposed in the recess 12B and an elastic member 70 is provided between the rotary shaft 40 and the balancer-integrated bush 60.

The discharge housing 13 has a bottomed cylindrical shape and is connected to the motor housing 11 so as to close the rear end of the motor housing 11. An outlet port 13B is formed through the discharge housing 13. A discharge chamber 13A is formed between the compression mechanism 20 and the discharge housing 13. The discharge chamber 13A is in communication with an external refrigeration circuit through the outlet port 13B.

The compression mechanism 20 includes a movable scroll member 21 and a fixed scroll member 22 that are disposed in facing relation to each other. The compression mechanism 20 is disposed adjacent to the end surface 42 of the rotary shaft 40. The movable scroll member 21 includes an end plate 21A and a spiral-shaped movable scroll wrap 21B that extends from the end plate 21A. The fixed scroll member 22 is fixed to the motor housing 11 and includes an end plate 22A and a spiral-shaped fixed scroll wrap 22B that extends from the end plate 22A. A discharge port 23A is formed through the end plate 22A of the fixed scroll member 22 in communication with the discharge chamber 13A. A compression chamber 20A is formed between the movable scroll member 21 and the fixed scroll member 22 by engagement of the fixed scroll wrap 22B with the movable scroll wrap 21B.

The discharge port 23A is formed between the compression chamber 20A and the discharge chamber 13A thereby to provide a fluid communication therebetween. A discharge valve 50 which opens or closes the discharge port 23A is provided on the discharge port 23A on the side facing the discharge chamber 13A. When refrigerant gas drawn into the compression chamber 20A is compressed there, the compressed refrigerant gas pushes open the discharge valve 50 and is discharged into the discharge chamber 13A through the discharge port 23A.

The electric motor 30 includes a stator coil 31 and a rotor 32, and the electric motor 30 is disposed adjacent to the end surface 41 of the rotary shaft 40. The stator coil 31 is disposed on the outer periphery of the rotor 32. The rotor 32 is fixed to the rotary shaft 40 and rotated integrally. A coil wire of the electric motor 30 is connected to a motor driving circuit 15A via a lead wire 15D, a cluster block 15C and a terminal 15B. The motor driving circuit 15A drives the electric motor 30, and the rotary shaft 40 is rotated, accordingly.

An eccentric pin 43 is formed extending from the end surface 42 of the rotary shaft 40. The eccentric pin 43 is disposed eccentrically with respect to the axis of the rotary shaft 40. The eccentric pin 43 extends towards the compression mechanism 20 in axial direction of the rotary shaft 40. The aforementioned balancer-integrated bush 60 is revolvably mounted on the eccentric pin 43 and revolvable between the eccentric pin 43 and the movable scroll member 21 by receiving rotational force from the rotary shaft 40 via the eccentric pin 43.

The balancer-integrated bush 60 includes a bush 62 and a balancer 65. The movable scroll member 21 is rotatably mounted on the bush 62 via a bearing 45A. When the rotary shaft 40 rotates, the bush 62 is revolved about the eccentric pin 43 and the movable scroll member 21 makes an orbital movement by virtue of the eccentric pin 43 and the bush 62. Because the movable scroll member 21 is prevented from rotating on its own axis by anti-rotation mechanism 21C, the movable scroll member 21 orbits relative to the fixed scroll member 22.

The line contact portion between the movable scroll wrap 21B of the movable scroll member 21 and the fixed scroll wrap 22B of the fixed scroll member 22 is moved gradually towards the center of the scroll members 21, 22. Accordingly, the compression chamber 20A moves toward the center while reducing the volume thereof. Therefore the refrigerant gas drawn into the compression chamber 20A through the suction port (not shown) is moved toward the discharge port 23A formed at the center of the end plate 22A of the fixed scroll member 22, while being compressed. The, compressed refrigerant gas pushes open the discharge valve 50 at the discharge port 23A and is discharged into the discharge chamber 13A. Then, the refrigerant gas is discharged out to the external refrigeration circuit through the outlet port 13B.

The balancer-integrated bush 60 will be described in detail with reference to FIGS. 2 to 8. FIG. 2 is a plan view of the balancer-integrated bush 60 in the compressor 100 as viewed from the electric motor 30 side. For the convenience of the description, the rotary shaft 40 is shown by a chain double-dashed line and the elastic member 70 formed between the rotary shaft 40 and the balancer-integrated bush 60 is shown by a dotted line in FIG. 2. FIG. 3 is a cross-sectional view of the rotary shaft 40, the balancer-integrated bush 60 and the elastic member 70. FIG. 4 is an exploded perspective view of the rotary shaft 40, the balancer-integrated bush 60 and the elastic member 70.

As shown in FIGS. 2 to 4, the balancer-integrated bush 60 includes the bush 62 and the balancer 65. The bush 62 and the balancer 65 are formed integrally. Referring to FIG. 2, the balancer-integrated bush 60 shown in plan view is shaped substantially symmetrical with respect to an axial line CL shown by dashed line. An eccentric hole 64 is formed in the bush 62 of the balancer-integrated bush 60 with the axial center C64 of the eccentric hole 64 offset from the axial center of the bush 62.

The bush 62 has a cylindrical shape and the movable scroll member 21 is rotatably mounted on the bush 62 via the bearing 45A (FIG. 1). The eccentric hole 64 is formed in the bush 62 on the side thereof that faces the end surface 42 of the rotary shaft 40. The eccentric hole 64 is formed eccentrically with respect to the axial center C62 of the bush 62.

The eccentric pin 43 is formed extending from the end of the rotary shaft 40 (FIGS. 3, 4). The end surface 42 of the rotary shaft 40, which is shown by a chain double-dashed line in FIG. 2, has a circle shape with a radius R40 with axis C40 as a center. The eccentric pin 43 is disposed eccentrically with respect to the axis C40 of the rotary shaft 40. The end of the eccentric pin 43 is inserted in the eccentric hole 64 so that balancer-integrated bush 60 mounted on the eccentric pin 43. The axial dimension of the eccentric pin 43 is larger than the depth of the eccentric hole 64, so that part of the eccentric pin 43 which is adjacent to the end surface 42 of the rotary shaft 40 is exposed when the eccentric pin 43 is inserted into the eccentric hole 64 (Refer to FIG. 3).

The balancer 65 is formed closer to the rotary shaft 40 than the bush 62 in the axial direction of the rotary shaft 40. The balancer 65 has a plate-like shape in a side view and has a fan shape in plan view.

The balancer 65 includes a main body 65B and a projecting portion 65A. The projecting portion 65A is formed only on the outer periphery of the balancer 65. The projecting portion 65A extends in axial direction towards the rotary shaft 40 parallel to the rotary shaft 40.

The balancer 65 has a concave circular surface 66 facing the outer peripheral surface of the eccentric pin 43, a flat surface 67 extending perpendicularly to the surface 66, a concave circular surface 68 extending perpendicularly to the surface 67 in the axial direction of the rotary shaft 40 and a flat surface 69 extending perpendicularly to the surface 68. The surface 66 extends parallel to the axis C40 of the rotary shaft 40 (FIG. 2). The surface 67 faces the end surface 42 of the rotary shaft 40. The surface 67 corresponds to a first surface of the present invention. The surfaces 66 and 67 form a part of the surface of the main body 65B, respectively. A clearance is formed between the surface 67 and the end surface 42 of the rotary shaft 40. A fitting hole 67A is formed in the main body 65B of the balancer 65 to open in the surface 67 and one end of the elastic member 70 is fitted in the fitting hole 67A.

The surface 68 faces the outer periphery of the rotary shaft 40. A clearance is formed between the surface 68 and the outer periphery of the rotary shaft 40. The surface 68 is curved in a complementary relation to the outer peripheral surface of the rotary shaft 40. In other words, the surface 67 and the surface 68 cooperate to form a recess 61 (FIG. 3) that receives therein the rear end of the rotary shaft 40. The surface 69 is formed only on the outer periphery of the fan-shaped balancer 65. The surfaces 68 and 69 form a part of the surface of the projecting portion 65A, respectively.

Referring to the FIG. 2, the point C65 is the center of an arc having a radius R69 and forming a part of the fan shape of the balancer 65. The point C65 is also the center of an arc having a radius R68 and forming a part of a fan shape having the same center angle as the fan shape of the balancer 65. The shape of the surface 69 substantially corresponds to a fan shape that may be formed by removing the fan shape with the radius R68 from the fan shape with radius R69.

A fitting hole 42B is formed in the rotary shaft 40 and the other end of the elastic member 70 is fitted in the fitting hole 42B. The elastic member 70 has a cylindrical shape. The inner diameters of the fitting hole 42B formed in the rotary shaft 40 and the fitting hole 67A formed in the balancer-integrated bush 60 are substantially the same as the outer diameter of the elastic member 70 and the elastic member 70 is press-fitted in these fitting holes 42B, 67A. The fitting holes 42B, 67A correspond to a first shaft recess and a first bush recess, respectively, of the present invention.

The fitting hole 42B and the fitting hole 67A are formed at such positions that, when the elastic member 70 is fitted in the holes, the balancer-integrated bush 60 is rotatable relative to the rotary shaft 40 in the direction indicated by arrow DR2 in FIG. 2. For example, the fitting hole 67A is disposed on the left side to the axial line CL and the fitting hole 42B is disposed on the right side thereto as seen in FIG. 2. Press-fitting the elastic member 70 in the fitting holes 42B, 67A, the balancer-integrated bush 60 is urged so as to revolve about the eccentric pin 43 relative to the rotary shaft 40 in the direction of the arrow DR2.

Arrow DR1 in FIG. 2 shows the direction in which the rotary shaft 40 is driven to rotate by the electric motor 30 (FIG. 1). As mentioned above, the movable scroll member 21 (FIG. 1) is mounted orbitably on the bush 62 of the balancer-integrated bush 60 via the bearing 45A (FIG. 1). When the rotary shaft 40 rotates, the balancer-integrated bush 60 (bush 62) is revolved around the eccentric pin 43, and the movable scroll member 21 orbits through the eccentric pin 43 and the bush 62. In this case, the anti-rotation mechanism 21C (FIG. 1) prevents the rotation of the movable scroll 21 member.

The arrow direction DR2 is opposite to the arrow direction DR1 (the rotational direction of the rotary shaft 40). When the balancer-integrated bush 60 (bush 62) is revolved around the eccentric pin in the arrow direction DR2 relative to the rotary shaft 40, the movable scroll member 21 (bush 62) makes an orbiting movement with a large radius. When the balancer-integrated bush 60 is revolved around the eccentric pin 43 in the arrow direction DR 1 relative to the rotary shaft 40, on the other hand, the movable scroll member 21 makes an orbiting movement with a small radius.

In the present embodiment, a preload is always applied to the movable scroll member 21 via the balancer-integrated bush 60 in the direction that increases the orbital radius of the movable scroll member 21 by virtue of the elastic member 70 provided between the end surface 42 of the rotary shaft 40 and the surface 67 of the balancer-integrated bush 60 in an elastically deformed state. For the convenience of the explanation, the outer peripheral of the rotary shaft 40 and the surface 68 of the balancer-integrated bush 60 are shown spaced apart from each other in FIG. 2. In actuality, the outer periphery of the rotary shaft 40 and the surface 68 of the balancer-integrated bush 60 are pressed against each other by the preload of the elastic member 70 in a state shown in FIG. 8.

The elastic member 70 is made of a resin or a rubber that is compatible with the refrigerant and the lubricant used in the compressor 100. For example, HNBR, NBR and EPDM may be used for the elastic member 70. According to the present invention, however, any material that has above compatibility may be used. If adequate preload cannot be obtain due to the material or the shape of the elastic member 70, any suitable metal may be used as a center core to increase the rigidity of the elastic member 70.

Referring to FIG. 5 showing the movable scroll wrap 21B of the movable scroll member 21 and the fixed scroll wrap 22B of the fixed scroll member 22 in plan view, the movable scroll wrap 21B is always urged so as to increase the orbital radius due to the preload of the elastic member 70. In the state shown in FIG. 5, the movable scroll wrap 21B is in contact with the fixed scroll wrap 22B at an appropriate contact pressure at a point P.

Referring to FIGS. 6 to 8, other dimensional relations of the rotary shaft 40 and the balancer-integrated bush 60 will be described. For the convenience of the explanation, the fitting hole 42B (FIG. 2), the fitting hole 67A and the elastic member 70 are omitted from illustration in FIGS. 6 to 8.

In this embodiment, L68A is the distance between the axial center C64 of the eccentric hole 64 and the edge end 68A of the surface 68 on the leading side thereof with respect to the arrow moving direction DR2. L68B is the distance between the axial center C64 of the eccentric hole 64 and the edge end 68B of the surface 68 on the leading side thereof with respect to the arrow moving direction DR1. PLE is the distance between the axial center of the eccentric pin 43 and the point PE that lies on the outer periphery of the rotary shaft 40 and is located furthest from the axial center of the eccentric pin 43 (or the axial center C43). The distance PLE is greater than either of the distance L68A and L68B.

Referring to FIGS. 6 and 7, if the balancer-integrated bush 60 is revolved about the eccentric pin 43 in the arrow direction DR1 (AR1) relative to the rotary shaft 40, the orbiting angle of the movable scroll member 21 is small. The rotation amount of the balancer-integrated bush 60 is restricted by the contact of the outer periphery of the rotary shaft 40 with the edge end 68A of the surface 68 of the balancer-integrated bush 60.

Referring to FIGS. 6 and 8, the orbital angle of the movable scroll member 21 increases when the balancer-integrated bush 60 revolves about the eccentric pin 43 in the arrow direction DR2 (AR2) relative to the rotary shaft 40. The revolution amount of the balancer-integrated bush 60 is restricted by the contact of the outer periphery of the rotary shaft 40 with the edge end 68B of the surface 68 of the balancer-integrated bush 60.

In this embodiment, the position of the eccentric pin 43, the position and the outer diameter of the rotary shaft 40 and the position and the radius of curvature of the surface 68 are established so as to fulfill the above dimensional relations and, therefore, the upper limit and the lower limit of the variable orbital radius of the movable scroll member 21 is restricted. The balancer-integrated bush 60 is revolvable while allowing variation of the orbiting radius of the movable scroll member 21 within the above range of the upper and lower limits.

The elastic member 70 provided between the fitting hole 42B of the rotary shaft 40 and the fitting hole 67A of the balancer-integrated bush 60 applies a preload to the movable scroll member 21 that causes the balancer-integrated bush 60 to revolve about the eccentric pin 43 in the arrow direction DR2 (or in the direction that increases the orbital radius of the movable scroll member 21) by virtue of the elasticity of the elastic member 70. The outer periphery of the rotary shaft 40 and the surface 68 of the balancer-integrated bush 60 are pressed against each other by the preload of the elastic member 70, so that the rotary shaft 40 and the balancer-integrated bush 60 are kept in the state shown in FIG. 8.

When the rotation of the rotary shaft 40 is stopped, the balancer-integrated bush 60 tends to continue to revolve in the arrow direction DR1 by inertia. Unless any effective measures is taken, the balancer-integrated bush 60 continues to revolve about the eccentric pin 43 in the arrow direction DR1 and the surface 68 of the balancer-integrated bush 60 collides against the outer periphery of the rotary shaft 40, thus generating an abnormal noise.

In this embodiment, the revolution of the balancer-integrated bush 60 in the arrow direction of DR1 by inertia is prevented by the preload of the elastic member 70 or by a load urging the balancer-integrated bush 60 to revolve in the arrow direction of DR2. When the rotary shaft 40 is stopped, a load is applied to keep the surface 68 of the balancer-integrated bush 60 and the outer periphery of the rotary shaft 40 to be in contact, thereby preventing abnormal noise development.

FIGS. 9 and 10 are a cross-sectional view and a plan view, respectively, showing the rotary shaft 40 and the balancer-integrated bush 60 of a compressor 101 provided as a comparative example. FIG. 11 is a plan view of the movable scroll wrap 21B of the movable scroll member 21 and the fixed scroll wrap 22B of the fixed scroll member 22. The compressor 101 shown in FIG. 9 through 11 is not configured to utilize the preload of the elastic member 70.

In the compressor 101 having no elastic member, the outer periphery of the rotary shaft 40 and the surface 68 of the balancer-integrated bush 60 tend to be separated easily, as shown in FIG. 10, when the compressor 101 is stopped. In addition, while the compressor 101 is in a stopped state, the movable scroll wrap 21B of the movable scroll member 21 and the fixed scroll wrap 22B of the fixed scroll member 22 tend to be separated, as shown in FIG. 11. When the compressor 101 is started in this state, the surface 68 of the balancer-integrated bush 60 and the outer periphery of the rotary shaft 40 collide against each other and generate an abnormal noise. Specifically the compressor 101 generates noise when the state of the compressor 101 is changed from FIG. 10 to FIG. 7.

The preload of the elastic member 70 is also effective when the compressor 100 is started. In the compressor 100 of the present embodiment, the outer periphery of the rotary shaft 40 and the surface 68 of the balancer-integrated bush 60 are pressed against each other by the preload of the elastic member 70 in the state, as shown in FIG. 8, while the compressor 100 is in a stopped state. Therefore, the abnormal noise is hardly generated during a start-up of the compressor 100 because of the preload that acts to keep the outer periphery of the rotary shaft 40 and the surface 68 of the balancer-integrated bush 60 to be in contact with each other.

Furthermore, the preload of the elastic member 70 is also effective during the operation of the compressor 100. When the cooling load of the compressor 100 is small, the rotary shaft 40 is rotated at a low speed. If it were not for the elastic member 70, it becomes difficult for the fixed and movable scroll wraps 22B, 21B to be kept in contact with each other with an appropriate contact pressure, as a result of which the compression performance of the compressor 100 is decreased. Meanwhile, the preload of the elastic member 70 enables the orbital radius of the movable scroll member 21 (bush 62) to be increased during the rotation of the rotary shaft 40 at a low speed and allows the scroll wraps 22B, 21B to be kept in contact with each other with an appropriate contact pressure, thus preventing a decrease in the compression performance of the compressor 100.

Providing the elastic member 70 between the rotary shaft 40 and the balancer-integrated bush 60 only requires to form the fitting hole 42B and the fitting hole 67A in the rotary shaft 40 and the balancer-integrated bush 60 respectively, and to press-fit the elastic member 70 in these holes 42B, 67A. Thus, the manufacturing and the assembly of the compressor may be accomplished with ease.

A second embodiment will be described with reference to FIGS. 12 to 14. The compressor of the second embodiment is designated by reference numeral 102. In the above-described first embodiment, the elastic member 70 is provided between the outer periphery of the rotary shaft 40 and the surface 68 of the balancer-integrated bush 60. The surface 68 corresponds to a second surface of the present invention. In the second embodiment, a fitting hole 40K is formed in the rotary shaft 40 from the outer periphery of the rotary shaft 40, and the elastic member 70 is provided between the fitting hole 40K and the surface 68 of the balancer-integrated bush 60. The fitting hole 40K corresponds to a second shaft recess of the present invention. When the rotary shaft 40 and the balancer-integrated bush 60 are assembled, the elastic member 70 is positioned adjacent to the edge end 68B of the surface 68 of the balancer-integrated bush 60 that is on the leading side of the surface 69 with respect to the moving direction DR1.

Also in the second embodiment, the movable scroll wrap 21B of the movable scroll member 21 is always urged by the preload of the elastic member 70 in the direction that increases the orbital radius of the movable scroll member 21, so that the same effects as those of the above-described first embodiment are accomplished. Instead of the fitting hole 40K, a recess may be formed in the surface of the balancer-integrated bush 60 to receive the elastic member 70. This recess corresponds to the second bush recess of the present invention. Alternatively, the second shaft recess (40K) and the second bush recess may cooperate to receive the elastic member 70. Furthermore, the positions of the elastic member 70 may be determined according to any combination of the first embodiment and the second embodiment.

The above embodiments have been described as the compressor that is provided with a swing link mechanism in which the bush and the balancer are swingable relative to the eccentric pin. The technical concept of increasing the orbital radius of a movable scroll member of a scroll type compressor by using the preload of an elastic member such as 70 is also applicable to a slide link mechanism in which the bush and the balancer are slidable relative to the eccentric pin.

The above embodiments and other configurations have been described to show an example of the scroll type compressor of the present invention and are not intended to limit the scope of the invention. The scope of the present invention is defined in appended claims and intended to include equivalents and all changes and modification that fall within the scope of the present invention. 

What is claimed is:
 1. A scroll type compressor comprising: a housing; a rotary shaft rotatably supported in the housing; an eccentric pin projecting axially from an end surface of the rotary shaft; a fixed scroll member fixed to the housing; a movable scroll member facing the fixed scroll and forming a compression chamber therewith; a balancer-integrated bush having an eccentric hole to receive the eccentric pin and disposed between the eccentric pin and the movable scroll, the balancer-integrated bush being configured to receive rotational force from the rotary shaft to cause the movable scroll member to make an orbital movement; and an elastic member provided between the rotary shaft and the balancer-integrated bush in an elastically deformed state to always apply a preload to the movable scroll member via the balancer-integrated bush in a direction that increases an orbital radius of the movable scroll member.
 2. The scroll type compressor according to claim 1, wherein the balancer-integrated bush has a first surface facing the end surface of the rotary shaft, wherein the end surface is provided with a first shaft recess and the first surface is provided with a first bush recess, wherein the first shaft recess and the first bush recess cooperate to receive the elastic member.
 3. The scroll type compressor according to claim 1, wherein the balancer-integrated bush has a second surface facing an outer peripheral surface of the rotary shaft, wherein the outer peripheral surface is provided with a second shaft recess and/or the second surface is provided with a second bush recess, wherein at least one of the second shaft recess and the second bush recess receives the elastic member. 